A method for controlling a brake system is described in German Published Patent Application No. 196 51 154, in which is provided a pump that is operated by an electric motor and can be turned on and off, with the pump overtravel time after shutdown being determined and the control signals for braking force buildup and release, respectively, being corrected as a function of the overtravel time. The purpose of this method is to estimate the temperature of the brake system. Electrohydraulic brake systems in which hydraulic fluid is injected from an accumulator into the corresponding wheel brake cylinder via a valve arrangement are not the object of this publication.
A method for controlling the brake system of a vehicle, in which at least one control signal having at least one variable parameter is used to build up and/or release pressure, is described in German Published Patent Application No. 196 04 126. The at least one parameter is corrected as a function of at least one quantity influencing the pressure change dynamics. In particular, the temperature of the hydraulic system and the ambient temperature, respectively, are given as influencing quantities. This publication also does not discuss the control of electrohydraulic brake systems.
It is known that the function of electrohydraulic brake systems is limited at low temperatures, and that viscosity of the brake fluid greatly increases at these temperatures. Pressure compensation procedures can be introduced only slowly in this case, significantly reducing the effect of provided valves or a pump used to charge the accumulator of the electrohydraulic brake system. The function of an electrohydraulic brake system is also limited at high temperatures, since the electric elements used have only a limited service life at high temperatures.
It has been shown that the related art cited above does not produce optimum results in every respect as far as the special problems of an electrohydraulic brake system are concerned.